Materials may be characterized in terms of bulk properties and surface properties. The overall properties of a material are controlled in significant part by the surface properties and the bulk properties of the material. The surface properties of a material are largely controlled by the surface chemistry and surface structure of the material. The bulk properties of a material are largely controlled by the bulk chemistry and bulk structure of the material. It is sometimes desirable to modify the surface chemistry and/or surface structure of a material in order to produce certain surface properties. In addition, it is sometimes desirable to modify the bulk chemistry and/or bulk structure of a material in order to produce certain bulk properties.
Substrates including hair and skin are of interest in terms of surface and/or bulk modification. Substrates are repeatedly exposed to mechanical washings, chemical treatments and environmental conditions which are among the many factors that may result in the loss of the substrates desirable properties such as natural and synthetically created shine, luster and texture. Moreover, environmental factors may add to these effects and substantially contribute to weathered or damaged substrates. Acute damage to the surface of substrates including hair and skin may build over time, resulting in chronic damage.
Accordingly, there exists a need for compositions and methods to compensate for things such as F-layer and stratum corneum loss from hair fibers and skin, respectively, that provides a durable conditioning and protective benefit. Covalent modification of the surface properties of damaged substrates materials is one example of such an approach. There is also a need to protect, repair, and/or strengthen these materials. Modification of the surface of a material by locally forming an active material on the material surface by reacting one or more active components to create covalent bonds between the one or more active components and modification the bulk of a material by forming active material in a similar manner within the bulk of the material are promising approaches.